1. Field of the Art
This invention relates generally to an internal combustion engine and more particularly to a breather device of an engine in which a pressure chamber is disposed above the crank chamber.
2. Prior Art
In general, in a four-stroke-cycle engine, blow-bye gas filling the crank chamber is returned to the air suction system and caused to undergo recombustion. At the same time, the crank chamber is maintained at a negative pressure by the use of a breather device.
For example, there is disclosed in Japanese Utility Model Publication No. 41932/1986 a method which comprises conducting the blow-bye gas within the crank chamber into a pressure chamber (vacant chamber) provided above the crank chamber and then, after this blow-bye gas has pressed open a pressure-responsive valve (check valve) and flowed into a breather chamber, causing this blow-bye gas to recirculate into the air intake system thereby to undergo recombustion.
By the use of the breather device disclosed in this prior art, however, the oil content contained in the blow-bye gas in the crank chamber readily flows into the breather chamber, and an amply distinct gas/liquid separation effect cannot be obtained.
In another example as disclosed in Japanese Utility Model Laid-Open Publication No. 155616/1986, oil-blocking plates are parallelly affixed to the back surface or the entire surface of the pressure-responsive valve in order to attain gas/liquid separation. This method, however, has been accompanied by the problem of tendency of flowing of the oil content thus separated into the air intake system from the oil return passage because of spitting.